Process for activating catalytic surfaces



Patented May "18, 1943 rnocsss soitacnvnmc strnc i U AC S? is ,Marion flr'Gwynn, tama, Application-M 31, -19 m,

Serial No. 338,233

' 1.1- m r Claims; t l; 252-255 This invention relates to the preparation of highly' active hydrated aniilblack'catalytic sura chlorite.

faces or surface layers by treating afmetal such as cobalt ornickel with anaque'ous solution off l, The surfacesl are preferably in a 1 l lroughened, forairiinousj or oxidized state prior to 'the chlorite treatment. The chlorite'treated surfaces or surface layers may be 'used in "hydroflning, i. e., hydrogenating and/or'refiningoils andlother carbonaceous compounds, particularly in sulphur sensitivehydrofiningl -TheS e Sju1'faGe layers, especially 'in conjunctionfwith a'proinoter for dehydration; areextraordinarily catalytic" for the conversion of water gas-to light hydrocarbons and like compounds The treatedsurface layers may'also beu s'ed as reagentsl as for example V in ;t he formation of. metallic's'ulphides or cari such halite solutions neither extremely acidic-nor ex-' tremelyalkaline. Withinthes limits, I find that "increasing the alkalinity of the chlorite solution lutions are'undesirable. I prefer, to use improves jthe adherence, decreases the metal o ses by solubility, but inhibits the depth of the activated film and the attack tin untreated metal.

When the metallic surface is pretreated assubsequently describedll preier touse" a dilute alkaline halite solutionjior example a sodium chlorite solution or" a concentrated sodium chlorite a solution to which has been added dilute alkali.

However, I may also use acid chlorite-som f tans, particularly when the metal 1 salt or the blackening nickel or topm- 'Althoughasmall acid j is insoluble, for example oxalic acid when portion ofthe Ymet'al maybe carriedintdsolu- Q bonyls, or as fadsorption or purifying agents, as in the treatment of vegetable or animal 2 31 rides before steam deodoriz ation, or as whenqdoc:

tor sweetening light petroleum or like clistillates;

or as tower packing or otherwise.

7U. s. Patent #2,191,464,lss ued to file February f 27, 1940, describes a similar used! highly alka i-line hypochlorites or hypobroznites. Jam able to For example,-iI may prepar flhishlyactive hy- -drated and blacktflxed catalytic surfacesor surface layers by preliminarily treatingia metal such was cobaltor nickel in a foraminate stateto form c an adherent surface layer, which is moderately catalytic w th or withoutigentle roasting. The surface comprising the preliminarily treated sur} face layer is then oxidized until highly" catalytic -lyst produced inthis way without further chemical treatmentis ready for use in hydrofiningioption, a mixtureot oxalic acid-and sodium chlorite has an advantage of rapid and deep peroxidation, and of requiringlittle or no preliininary oxidizing treatment. Thusan acid chlorite treatment isparticiIIaIly'useIuI as afirstor prelimi "nary treatment, which maybe followed by an I alkaline chloritefltr'eatinent." jThu's hydroxide,

. activate adherent surfaces with chlorit at high? u er temperatures and conce tr t n and with V relatively much less alkali; r a v carbonate and oxalate ions areuseful additions toiaqueo'us chlorite solutions. threeof-these anions are complex anci containnoxygen but no chlorine; n

w and oxalatesare watr'insoluble.

Myinvention isnot limited *tobobalt and nickel; it being within the contemplation of myinvention also tofuseflmetal alloys of face center 1 cubic crystal latticawhich are neither extreme- V v with an aqueous chlorite solution. I The chlorite i asolution preferred contains-a limiteqe rces's of alkali of insufll ci ent concentration to, exert a r solvent action onthe surface layer. The cata-V 1y electropositive nor extremel electronegative, especially if they are readily-reduci-ble-and if they are secondarily'ferromagnetic like cobalt or nickel in the metallic state. For example; I .mayuse a readily reducible mixture of hydrated 'andoiiidiz'able' compounds containing copper and manganese, which mixture is secondarily ferromagnetic when reduced to the metallic state.

erations and maintains its activity substantially i uniform during hydronning until spent. Instead of startingwith a new metal surface or with {a surface comprising a readily oxidiz'able compound of the-catalyticmetal Imay start with surfaces which have been 7 used in hydrogenation and which must be reactivated. When my, invention is used to reactivate catalyst surfaces containing sulphur; I preferto remove mostoi the; sulphur prior to the chlorite treatment, aswillflbe describedrw ,According my inventiongfinstead of using a chlorite solution I may use chlorinedioxide or Y a other halites, particularly: bromites; to produce catalysts, and these catalysts are usable .as such without requiring. further chemical treatment.

t iibctremely alkaline halite solutions m y be con- 1 centrated with respect to sodium hydroxide, and

I will now givesome examples byway of illustration of how my invention 1st) bepracticed, but I am not to be limited thereto, as they may be modified in many particularswithout departing from the spirit or the invention. The resultings activated sur faces'have specific as well as 'general usage. a"

sam l 1 A highly active-V catalyst promoted foridehyf ration and particularly catalytic for the conversion of carbon monoxide and hydrogen to hydrocarbons, such as-motor fuels, and containing hydrated cobalt silicate and hydrated cobalt ox: .idS, is prepared as follows: l

'A, new cobaltor cobalt coated mass andiwith the surface'layer in aforaminate state, is'con nected as the anode in an electrolyte: composed of commercial water glass at about 30 C and a fiio frlcs ickelo'r cobalt hydrokidesfcarbonates current density of about milliamperes per square centimeter i applied for sufiicient time to form a deep blue coating containing hydrated silica and hydrated silicate of cobalt on the surface. The treated mass is removed, drained and immersed in a highly alkaline aqueous solution maintained at room temperature made by mixing fore the water wash, other means such as -a salt ;--1- water wash may be employed to facilitate removal of the anions of the halite solution without loss of catalyst. The washed surface layer is highly catalytic without further treatment. when the treated catalytic mass is used for hydrofining. any water remaining on the catalytic surface is preferably removed with warmed hydrogen.

Other concentrated alkaline electrolytes depositing a dehydration promoter in the surface layer 'may be substituted for the water glass, particularly those concentrated and colloidal and which gel on the slight addition of acid.

Example 2 A cobalt or cobalt coated mass is connected as the anode in an electrolyte composed of 5 normal aqueous hydrofluoric acid at room temperature.

The current densityand voltage are then adjusted to form a deep adherent film on the cobalt mass. For instance, about 4 volts are first applied and as the current density or current efliciency diminishes, the potential may be increased continuously or discontinuously to 5 or 6 volts or even much higher, preferably maintaining the .bath cold and the product of the current density and current efficiency no greater than about that of the original. product thereof. When the current efliciency substantially decreases or when a deep black surface layer is formed the mass is withdrawn, drained and washed, and then treated with the halite solution and finished as given in Example 1.

Other strong acid electrolytes may be substituted for hydrofluoric acid, preferably decomposable land in a concentration at which the acbalt. A relatively shallow layer of adherent nickel hydroxide, or a somewhat thicker layer of adherent cobalt hydroxide suflices to initiate deeper oxidation of the catalytic surface with more alkaline and cooler halite solutions.

The reaction of the halite compounds with the I surface layers appears to be partially autocatalytic and hence those agencies which initiate activation are useful. For instance, the more activatable compounds in or formed on the metal surfaces by proper pretreatments, during their reaction with the halite solution initiate the activation or oxidation of the more difilcultly activatable compounds or by the underlying metal itself. Successive reactivations after. using the catalyst for hydrogenation are generally accompanied by increases of the depth of the surface layer and receptivity to activation.

Example 3 surface and to form a surface layer containing tivity coeflicient is low. Such acids with or with-.

out impressed electrical potential may be used to treat these and other surfaces prior t halite activation, as for example those spent in hydrofining.

Hydration of the surface layer prior to halite activation may be obtained as in the previous examples, or during reaction with steam, or by other methods or combinations of methods. Hy.

' dration is particularly desirable if the oxidizable compounds of the catalytic metal in the surface layer before treatment are salts and are not readily reducible to the metallic state unless oxidized. If the salts comprising said surface layer v before halite treatment are neither readily reducible to the metallic state not insoluble in the halite solution, they should be gently roasted until mcderately catalytic, as with the nitrates in Examples 3 or a (to be later given herein).

nickel nitrate. The surface layer, without washing, is then dried and gently heated in a current of air at near the lowest temperature required to evolve fumes and decompose a substantial portion of the resulting nickel nitrate and darken the mass, for instance at about 300 C. The resulting surface layer may be further activated by contacting with a more active halite than the one given in Example 1 in order to initiate the oxidation, as for instance, a more concentrated or less alkaline solution of chlorite. Specifically, the pretreated nickel mass is immersed in a heated alkaline aqueous solution consisting principally-of sodium carbonate and sodium chlorite.

If blackening does not begin within a 'few minutes, the alkaline chlorite solution-is further heated, preferably without boiling, until the blackening is initiated. Then as the reaction proceeds the stability of the alkaline chlorite solution may be increased as by cooling or decreasing the chlorite-concentration of the solution. The blackened mass is then withdrawn, drained and washed as given in Example 1.

Example 4 A new cobalt or cobalt coated mass is pretreated several hours with the vapors of boiling concentrated nitric acid to pit the surface and to form a surface layer containing cobalt nitrate, as described in my copending application, Serial Number 240,007, new U. S. Patent 2,270,874, granted January 27, 1942. The surface layer, without washing, is then dried and gently heated in a current of air at near the lowest temperature required to evolve fumes and decompose most of the resulting cobalt nitrate, for instance at about 300 C. Such moderately catalytic surface is further activated by contacting with a halite similar in stability to that described in Example 3.

The blackened'mass is then withdrawn, drainedand washed as given in Example 1. I

A decomposed cobalt nitrate surface may be electrolytically treated, followed by chlorite oxidation and washing as given in Example 1 or 2. Other metalsmay be activated in the same manner, for example a decomposed nickel nitrate surface may be treated instead of the new cobalt mass given in Example 1. i

Afterthe halite treatment, a surface layer may be further chemically treated, for instance after the final washing in Example 2 or 3 or 4; the catalystmay be dipped in a strong aqueous solution of chromic acid, or ammonium molybdate or thiomolybdate, then withdrawn and allowed to drain.

Example 5 Powder catalyst, particularly black nickel catalyst supported'upon kiesulguhr, may be chlorite reactivated. For example black nickel catalyst used and spent in the hydrogenation of a glyceride, such as refined cottonseed, corn or soybean oil, is solvent extracted to remove the residual hydrogenated oil and accompanying organic impurities. The extracted catalyst is then stirred "surfaces may be diminished by other methods than my alkali control. a, For instance when the alkalinity is relatively small the solvent action of any free halous acid may be minimized by an unusual short time of contact so that the oxidized surface layer is relatively shallow. Or a surface layer may be contacted 'with a halite compound or chlorine dioxide in vapor form, preferably moist. p g

A halite treatment may be accompanied by other oxidizing agents or treatments. For instance wet oxygen or air may, be'mixed with gaseous chlorine dioxide and the mixture used to activate catalytic surfaces in the vapor phase. Or a surface layer undergoing activation maybe treated with both air and a halite solution. For

instance a chlorite solution may be continuously or intermittently sprayed over the surface undergoing activation.

i catalytic surface useful in hydrofining, which I What I claim is: 1. A process for preparing a highly active comprises activating a surface whose metal component is selected from the class which consists with a heated dilute alkaline aqueous sodium W chlorite solution until reactivated, and subsequently is .washed to remove said activating solute. When reused for-thehydrogenation of glycerides, the reactivated catalyst is preferably reduced in hydrogen prior to catalysis. If used for desulphurizing or for the hydrogenation of diisobutylene, benzene, phenol, or similar compounds, reduction of the catalyst, whether in powder orother form, may be undesirable prior to catalysis.

Before reactivating catalyst used for hydrogenating and/or purifying fatty or like compounds, the latter compounds or impurities may be removed or extracted as by refluxing with volatile hydrocarbons. Or more polar solvents such as dichlorethylene or acetone may be used, particularly for a final extraction or when using the catalyst as a purifying agent.

When the" surface layers are heavily sulphided,

of nickel, cobalt anda ferromagnetic and readily reducible alloy, with an aqueous halite solution.

A process as described in claim 1, in which the aqueous halite solution is a chlorite solution and also contains substantial quantities of a complex anion containing oxygen, but not halogen, the metal salt of the anion being substantially insoluble in water.

the major part of the sulphur is preferablyremoved prior tohalite reactivation. For instance,

a nickel surfacesulphided as described, in my U. S. Patent 2,174,5l0,may be substantially but incompletely desulphided by roasting with steam and/or air. Subsequently the surfaces may be blackenedand further desulphided by means of a chlorite treatment, for example an acid chlorite treat followed by an alkaline chlorite treatment.

Catalytic surfaces to be treateddo not have to be disturbed for reactivation. If'a vessel is lined with a catalytic surface, such liners may be activated. In the preparation of fixed catalyst 3. A method of activating catalytic surfaces whose metal component is selected from a class which consists of nickel, cobalt, and a ferromagnetic and readily reducible alloy, which comprises preparing an adherent catalytic surface by contacting the surface in an oxidizable and foraminate state, with a dilute alkaline halite solution.

4. A method of activating catalytic surfaces whose metal component is selected from the class which consists of nickel, cobalt, and ferromagnetic and readily reducible alloy, which com- 'prises the steps of gently roasting the surface until substantially converted to the oxide of the catalytic metal, and subsequently further oxidizing the surface with an aqueous, halite solution.

. 5. ,Amethod of activating catalytic surfaces whose metal component is selected from the class which consists of nickel, cobalt, and a ferromagnetic and readily reducible alloy, which' comprises the steps of roasting a metal sulphide surface with air and steam to convert most of said metal sulphide to the metal oxide, and subsequently treating with an aqueous chlorite solution to blacken and further remove sulphur from 'on metal, the metal prior to chemical activation may be machined so as to produce burrs or grooves or may be, worked as with heat and/ or alloying to produce fine longitudinal cracks. Fixed catalyst such as a foraminate base metal or rough inert solid whose surfaces contain nickel of cobalt or like metal, or catalytic surfaces prepared by 'the various methods of the art, may be activated or reactivated according to 'my invention. An

embly such as described in my c'opending app cation Serial Number 297,651, flled October 3, 1939, may be chlorite activated as described. The solvent action of halite solutions on the catalytic said surface. 6. A method as described in claim 5, in which the chlorite treatment is followed by treatment awith another aqueous chlorite solution more alkaline than the previous chlorite solution.

7; A process for preparing a highly active and adherent catalytic surface which comprises the steps of forming a surface layer which contains an oxidizable hydrated compound of a metal selected from the class which consists ofnickel,

cobalt, and a ferromagnetic and readily reduci ble alloy, and subsequently treating the surface with a dilute alkaline halite solution.

M. H- GWYNN. 

